CVE-2021-20590Network attack vector

Unauthenticated VNC access via crafted packets

Published Apr 22, 2021 · Updated Aug 3, 2024

Improper authentication in Mitsubishi Electric GOT VNC servers allows remote attackers to gain unauthorized access via crafted packets. The VNC server accepts a specially crafted packet without completing password authentication; Mitsubishi has not disclosed the packet field or validation error. Exploitation requires the VNC server function to be enabled and permits remote monitoring or control through the exposed VNC session.

CVSS severity5.9
Medium
EPSS probability1.27%
Next 30 days · Sep 17, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper authentication in Mitsubishi Electric GOT VNC servers allows remote attackers to gain unauthorized access via crafted packets. The VNC server accepts a specially crafted packet without completing password authentication; Mitsubishi has not disclosed the packet field or validation error. Exploitation requires the VNC server function to be enabled and permits remote monitoring or control through the exposed VNC session.

The record

CVE
CVE-2021-20590
Published
Apr 22, 2021
Updated
Aug 3, 2024
Vendor
Mitsubishi Electric Corporation
Product
GOT2000 Series GT21 model
Classifications
CWE-287, T1210
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 22, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=VNC server version 01.40.000 and prior

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Mitsubishi Electric Corporation · GOT2000 Series GT21 modelversion=VNC server version 01.40.000 and prior
Mitsubishi Electric Corporation · GOT2000 Series GT25 modelversion=VNC server version 01.39.010 and prior
Mitsubishi Electric Corporation · GOT2000 Series GT27 modelversion=VNC server version 01.39.010 and prior
Mitsubishi Electric Corporation · GOT SIMPLE Series GS21 modelversion=VNC server version 01.40.000 and prior

Published CVSS scores

7.5NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
4.3NIST National Vulnerability DatabaseAV:N/AC:M/Au:N/C:N/I:P/A:N
5.9Mitsubishi Electric CorporationCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-287Improper Authentication
T1210Exploitation of Remote Services

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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